The NYU Cancer Institute Proteomics Core Facility provides state-of the-art biological mass spectrometry analyses to cancer researchers at NYU to help them identify and characterize proteins of medical importance. The facility has identified many tens of thousands of proteins from SDS-PAGE gels, often at subpicomolar levels, by LC-MS/MS of proteins followed by MASCOT or BLAST homology database searching. The facility has also characterized posttranslational modifications such as phosphorylation, acylation, and glycosylation. In addition to its technical expertise, one of the strengths of the facility is its ability to advise clients in the design and interpretation of experiments so that useful data can be obtained and meaningful information can be had from these data. Reliance on cutting edge technology and its expert and dedicated staff allow these services to be performed in a cost effective manner. Indeed, many experiments by investigators at NYU and the NYU Cancer Institute could not have been done without the assistance of the facility. Recently the Facility has established a Clinical Proteomics Core for the detection of protein and peptide biomarkers for the early detection of cancer.